JPS6021605B2 - Manufacturing method of rubber modified vinyl resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a rubber-modified vinyl resin with excellent color toning properties.

In order to improve the impact resistance of hard and brittle vinyl polymers, it has been known that vinyl monomers are graft-polymerized in the presence of rubbery elastomers to produce so-called rubber-modified pinyl resins. It is being

However, the rubber-modified pinyl resin produced by such a conventional method is a vinyl polymer (meaning a homopolymer or a copolymer other than a graft copolymer).

Same below. ), it has achieved its purpose in terms of improved impact resistance compared to ), but on the other hand, the disadvantage is that the excellent color toning properties exhibited by vinyl polymers are reduced in rubber-modified vinyl resins. ing. To explain in more detail, vinyl polymers and rubber-modified vinyl resins are usually uniformly colored with pigments, etc., and there is no difference in color tone no matter which direction the molded product is observed.

However, it is well known that when rubber-modified vinyl resins are colored in a particular color tone, particularly black, the color tone appears to differ significantly depending on the viewing direction. For example, if a rubber-modified vinyl resin is colored black with carbon black and then molded by injection molding, the color tone of the molded product may appear green or blue, mixed with black, depending on the viewing direction. When a boss or the like is attached to a molded product, a phenomenon is observed in which the concave portion of the molded surface due to shrinkage during cooling exhibits a green or blue color, which is different from the original color tone. The cause of this phenomenon is
As a result of the rubber-like elastomer particles dispersed in the rubber-modified vinyl polymer being arranged in layers in a specific direction during injection molding, the incident light is reflected in a specific direction, causing the reflected light to interfere. It is thought that this is because it exhibits a color tone other than that of the pigment.

Conventionally, as a countermeasure when such a phenomenon occurs, the amount of pigment used is increased so that the color tone different from the actual color tone of the pot does not stand on its own.

However, this method does not completely solve the problem,
In addition, when the amount of pigment used is large, the impact resistance of the molded product is reduced, which reduces the commercial value of the rubber-modified pinyl resin. An object of the present invention is to improve the drawbacks of the prior art and provide a method for producing an impact-resistant rubber-modified pinyl resin with excellent color toning properties. That is, the present invention provides a method for producing an impact-resistant rubber-modified vinyl resin in which a rubber-like elastomer is melted into a vinyl monomer, bulk polymerization is carried out under a vacuum, and then suspension polymerization is carried out. After the rubber phase becomes a dispersed phase in the polymerization process, water is added to the bulk polymerization reaction product in an amount that does not form a continuous phase of water, and the mixture is incubated for at least 15 minutes to carry out bulk polymerization in a hydrated state. The present invention provides a method for producing an impact-resistant rubber-modified vinyl resin, which includes a step of forming a mixture.

Before explaining the structure of the present invention, a conventional method for producing a rubber-modified vinyl resin will be explained.

First, a rubbery elastomer is dissolved in a vinyl monomer, and then bulk polymerization is carried out under a dosing system.

In this bulk polymerization step, the contents of the polymerization tank were a homogeneous solution of vinyl monomer with rubbery elastomer dissolved therein before polymerization, but as the polymerization reaction progressed, the vinyl polymer was dissolved. The vinyl monomer obtained becomes a spherical dispersed phase and separates from the above solution, so the vinyl monomer phase in which the rubbery elastomer is dissolved (hereinafter referred to as the rubbery elastomer phase) and the vinyl polymer are separated. The resulting dispersion consists of two phases: a vinyl monomer phase (hereinafter abbreviated as vinyl polymer phase) in which In this case, a vinyl polymer phase is dispersed in a rubbery elastomer phase. As the polymerization further progresses, the vinyl polymer phase becomes larger and more numerous, and finally forms a continuous phase. It becomes a state where it forms.

As the polymerization progresses, the amount of the vinyl polymer phase increases further, and finally, the vinyl polymer phase remains as a continuous phase and the rubbery elastomer phase is dispersed within it, resulting in so-called phase inversion. Ru. At this point, the dispersed phase of the rubbery elastomer is amorphous and consists of particles with a size of several tens to hundreds of Buddhas.
As the polymerization progresses further, the rubbery elastomer dispersed phase becomes spherical particles with a size of several degrees. When such a state is reached, the bulk polymerization mixture is suspended in a separately prepared aqueous phase containing a dispersant, or a large amount of water containing a dispersant is added to the bulk polymerization mixture to form a polymer. is suspended and the polymerization is completed by suspension polymerization to produce bead-shaped rubber-modified pinyl resin. The obtained rubber-modified vinyl resin in the form of beads is further blended with an antioxidant, a coloring agent, etc., formed into pellets using an extruder, and used as a variety of molding materials. In the method of the present invention, in the conventional bulk polymerization step, after the rubbery elastomer phase becomes a dispersed phase, water is added to the bulk polymerization mixture in an amount that does not form a continuous phase; This method is characterized by providing a process of continuing the worship of flies.

In the method of the present invention, the amount of water added to the bulk polymerization reaction product that does not form a continuous phase means that the added water exists in a dispersed state in the rubbery elastomer phase and the vinyl polymer phase. Although it specifically depends on the type of vinyl monomer, it is usually about 5 parts by weight to 10 parts by weight for a total of 10 parts by weight of the rubbery elastomer and vinyl monomer. corresponds to this.

Furthermore, if the amount of water added is too small, the effects of the present invention will not be fully manifested, so it is usually preferable to add 5 parts by weight or more. When the vinyl monomer is stainless steel, alpha methylstyrene, etc., 1 part by weight to 7 parts by weight is particularly preferred. Furthermore, in the method of the present invention, it is essential to add water at a specific stage of the bulk polymerization stage, that is, after the rubbery elastomer phase becomes a dispersed phase. Even if water is added before the rubbery elastomer becomes a dispersed phase, the effect of the present invention will not be achieved.

Further, water may be added at any time during the bulk polymerization stage as long as the rubbery elastomer phase has become a dispersed phase, and there is no need to specify the final stage of water addition.

However, the vinyl monomer content is usually 25 to 50% in the bulk polymerization process.
Therefore, it is practically preferable to add water at any time after the rubbery elastomer phase becomes a dispersed phase during the bulk polymerization stage and when the polymerization rate is within 50%. Of course, if, as in the prior art, a large amount of water containing dispersion water is added all at once after the bulk polymerization step is completed and the process proceeds to the suspension polymerization step, the effects of the present invention will not be achieved at all.

Further, even if water is additionally added in the suspension polymerization step, the effects of the present invention will not appear at all. An extreme case of water addition timing is to add some of the dispersant-containing water (the suspending medium for prior art suspension polymerizations) to the bulk polymerization mixture after the rubbery elastomer phase has become the dispersed phase. , water is added in an amount that does not form a continuous phase, and the suspension is continued for a certain period of time (described later), after which the remaining suspension medium (water containing a dispersant) is added to effect suspension. The effects of the present invention can also be achieved by completing the process.

In the method of the present invention, it is necessary to continue the hawk worship even after the addition of water.

Although it depends on the type of vinyl monomer, it is generally necessary to perform Nada-azusa for 15 minutes or more, preferably 30 minutes or more. If the incubation time after adding water is too short, the effects of the present invention will not be sufficiently manifested. In the conventional production method, when bulk polymerization is completed by adding a large amount of water containing a dispersant to the bulk polymer to make it into a suspension weight, the work time for adding water is reduced as much as possible to shorten the production time. The suspension is usually completed within 5 minutes by adding enough water to form a continuous phase. Therefore, in the prior art, even if a bulk polymerization mixture containing water in a quantitative range in which water does not form a continuous phase is formed at a certain moment, it is possible that this will persist for as long as the certain period of time specified in the present invention. Therefore, the effects of the present invention cannot be exhibited. Although the temperature at which water is added in the present invention is not particularly limited, when water is added at a temperature lower than the polymerization temperature, the effect of improving toning properties is remarkable. However, if water at too low a temperature is added, the polymerization temperature will drop significantly, and it will take a long time to raise the temperature to the polymerization temperature again, resulting in poor productivity of the polymerization apparatus. Therefore, the temperature of the water added is usually between 40 and 800°C.
0 is practical. Conventionally, a method of adding water from the initial stage of the bulk polymerization process has been known (for example, Japanese Patent Publication No. 52-15
4), but the purpose of these methods is to remove impurities by adding water from the initial stage of polymerization, and by adding water during a specific period from so-called phase inversion during bulk polymerization to the start of suspension polymerization, the resin There is no suggestion of improving the toning properties of.

It is not clear why the toning properties are improved by the production method of the present invention, but when water is added during the bulk polymerization process,
It is presumed that because the state of the bulk polymerization mixture changes microscopically, the rubbery elastomer phase that is being formed is in a different dispersed state than in the case of conventional production methods.

As a result, in the method of the present invention, the optical properties, especially the reflective properties, of the dispersed phase of the rubbery elastomer change to those that are less likely to cause optical interference, and therefore, unlike the rubber-modified pinyl resin produced by the conventional production method, It is estimated that the color toning failure phenomenon will no longer be exhibited. Examples of rubbery elastomers used in the present invention include polyptadiene (low cis polybutadiene and high cis polybutadiene), styrene-butadiene rubber (SBR), acrylic rubber, nitrile rubber,
Isof.

Examples include rubber, ethylene-propylene-gene terpolymer (EPDM), and the like. These may be used alone or in mixtures. The vinyl monomer used in the present invention is particularly preferably one that provides a hard and brittle polymer, such as styrene, alphamethylstyrene, chlorostyrene, methyl methacrylate, acrylonitrile, methacrylonitrile, etc. I can do it.

These may be used alone or as a mixture. Examples of combinations of rubbery elastomer and vinyl monomer to which the method of the present invention can be applied particularly preferably include polybutadiene-styrene, SBR-styrene, and polybutadiene-styrene-acrylonitrile. The ratio of the rubbery elastomer and vinyl monomer used in the present invention is not particularly limited, but is usually 1 by weight.
A range of :99 to 15:85 is preferred.

In the method of the present invention, various additives and auxiliary agents used in conventional manufacturing methods can be similarly used. For example, chain transfer agents such as Yuichi syaridodecyl mercabutane, polymerization initiators such as benzoyl peroxide, plasticizers such as liquid paraffin, dispersants such as polyvinyl alcohol, etc. are used during polymerization, and polymerization is terminated. When forming the latter beads into pellets, an antioxidant such as ditertiarybutylhydroxytoluene, a lubricant such as calcium stearate, etc. can be used in the same manner as in the conventional method. In the method of the present invention, conditions other than those mentioned above, such as polymerization temperature and strength, can be the same as those used in conventional methods.

For example, in bulk polymerization, the polymerization temperature is 90 to 130 pm, and the rotation speed of the flywheel is 40 to 60 pm. p. In addition, in the suspension polymerization step, the polymerization temperature is 0 to 150 pm, and the rotation speed of the key holder is 40 to 40 pm. p. m conditions may be adopted. The resin produced by the method of the present invention is mainly used for producing molded products by injection molding. In particular, it is suitably used for injection molded products such as radio housings and television housings that are toned in dark colors, and has high practical industrial value. Example 1 Polybutadiene (Nitsuboru 1202 manufactured by Nippon Zeon Co., Ltd.) 4.2K9 Styrene 56.8
k9 tertiary dodecyl mercaptan 0.06
K9 was charged and dissolved under heating at 65 degrees Celsius to form a homogeneous solution.

After that, the number of revolutions of the light main machine was increased to 15. p. m, and the temperature was raised to 150°C to carry out bulk polymerization.

When samples were taken at every IHr and observed using a phase contrast microscope, the polybutadiene phase became a dispersed phase at the point r after the start of polymerization (so-called phase inversion occurred). After polymerization starts
First, 60 qo of pure water 30k9 was injected using a gas pump. Although the internal temperature temporarily decreased, the temperature was raised again to 105° C., and polymerization was continued for a total of 10 hours from the start of polymerization. Thereafter, previously prepared suspension water having the following composition was introduced under pressure using a gear pump to suspend the bulk polymerization mixture. water
90k9 tertiary calcium phosphate
2.4k9 dicumyl/dioxide
0.12k9 The above suspension was heated to 120qo, and after the suspension operation, polymerization was continued, and then IHr was added at 140oo.
The mixture was heated to complete the polymerization. The obtained beads were chiseled and dried, and 0.5 parts of diterciabutylhydroxytoluene and 0 part of carbon black were added to 10 bases of dried beads.
．． The resulting mixture was made into pellets using an extruder.

Using the above pellets, impact resistance and color toning properties were evaluated by injection molding.

(1) Shape of molded product for evaluation of toning properties: A disc with a diameter of 70 legs and a thickness of 3 ribs,
On the same side of the disc, there are four legs, 3 mm long and 5 mm in diameter, spaced 90 degrees from each other and 2 mm apart from the center.

Since a concave portion is formed on the disc surface on the opposite side of the foot of the molded product due to shrinkage, the color tone of that portion was judged with the naked eye. The results were evaluated on a five-point scale, with the conventional method (comparative example 2 described below) being rated 1 (poor color toning properties).

■ Impact resistance measurement 5th place h/m x 5 h/m x 2.8 h
A striking core of 1'4 inch radius is applied to a square plate of /m and a constant load is dropped from above, and the energy is expressed as the energy at which 50% of the test piece breaks.

Fracture energy (kg - 伽) = Falling height of load (arc) x
Load (k9) Table 1 shows the evaluation results of the impact resistance and color toning properties of Example 1.

Comparative Examples 1 and 2 Rubber-modified vinyl resins were obtained in the same manner as in Example 1, except for the following differences.

That is, in Comparative Example 1, 30k9 of water is added to the IHr of bulk polymerization (before phase inversion). In Comparative Example 2, no water was added at the stage of bulk polymerization.

The same color toning test and impact resistance test as in Example 1 were conducted on each of the obtained rubber-modified vinyl resins. The results are shown in Table 1. Example 2 In Example 1, the number of ropes after adding water was changed to 20. p. m'
A rubber-modified vinyl resin of Example 2 was obtained by following the same procedure as in Example 1 except that the procedure of increasing the height was added.

Table 1 shows the results of a color toning test conducted in the same manner as in Example 1.
Table 1 Example 3 SBR (Tufden 2000 manufactured by Asahi Kasei Co., Ltd.) 4.2k9 was used in a polymerization tank with an internal volume of 150 and a rope sizing machine.
Styrene 42.6k
9 Acrylonitrile 14.2k9
Tertiary dodecyl mercaptan 0.3k9 was charged and dissolved in 690°C with porridge to form a homogeneous solution.

Next, set the number of flies to 20. p. m, and raise the temperature to 10,000
Bulk polymerization was carried out.

When samples were taken every IHr and observed using a phase contrast microscope, the SBR phase became a dispersed phase at the point where polymerization started.
After the start of polymerization, water at 70° C., prepared in advance as follows, was injected under pressure using a gear pump. water
30k9 tertiary calcium phosphate
Next, the number of ropes was 30. p. m, 3
I continued to worship the hawk for 0 minutes.

After that, the next suspension water was introduced under pressure to suspend the bulk polymerization mixture. water 90k
9 Tertiary Calcium Phosphate 1.8k9 Dicumyl/Goo Oxide 0.12k9 This suspension was heated to 110 qo to perform lees suspension polymerization, and further heated to 45 qo for 2 days to complete the polymerization. The obtained rubber-modified vinyl resin was subjected to a color toning test in the same manner as in Example 1, and the results are shown in Table 2. Comparative example 3 Example 2
It was manufactured in accordance with the same procedure as that of the same aircraft, with the following exceptions:

That is, after the start of polymerization, suspension water prepared in advance as follows is injected all at once using a gear pump. water
120k9 tertiary calcium phosphate 2.4k9 dicumyl/gu oxide
Table 2 shows the evaluation results of impact resistance and color toning of the rubber-modified vinyl resin obtained.

In addition, as a reference sample for evaluation, acrylonitrile-styrene copolymer (so-called AS resin: trade name LIGHTAC 100)
)It was used. Table 2

Claims (1)

[Scope of Claims] 1. In a method for producing a rubber-modified vinyl resin, in which a rubber-like elastomer is dissolved in a vinyl monomer, bulk polymerization is performed under stirring, and suspension polymerization is then carried out, in the bulk polymerization step. After the rubber phase forms a dispersed phase, a step of adding water to the bulk polymerization reaction product in a quantitative range in which water does not form a continuous phase and stirring for at least 15 minutes to form a water-containing bulk polymerization mixture. A method for producing a rubber-modified vinyl resin. 2. The method for producing a rubber-modified vinyl resin according to item 1, wherein the water is water that does not contain a dispersant. 3. A method for producing a rubber-modified vinyl resin, characterized in that the intensity of stirring after adding water as described in item 1 is made stronger than the intensity in the bulk polymerization step.